title: Acamprosate produces its anti-relapse effects via calcium.
abstract: Alcoholism is one of the most prevalent neuropsychiatric diseases, having an enormous health and socioeconomic impact. Along with a few other medications, acamprosate (Campral-calcium-bis (N-acetylhomotaurinate)) is clinically used in many countries for relapse prevention. Although there is accumulated evidence suggesting that acamprosate interferes with the glutamate system, the molecular mode of action still remains undefined. Here we show that acamprosate does not interact with proposed glutamate receptor mechanisms. In particular, acamprosate does not interact with NMDA receptors or metabotropic glutamate receptor group I. In three different preclinical animal models of either excessive alcohol drinking, alcohol-seeking, or relapse-like drinking behavior, we demonstrate that N-acetylhomotaurinate by itself is not an active psychotropic molecule. Hence, the sodium salt of N-acetylhomotaurinate (i) is ineffective in alcohol-preferring rats to reduce operant responding for ethanol, (ii) is ineffective in alcohol-seeking rats in a cue-induced reinstatement paradigm, (iii) and is ineffective in rats with an alcohol deprivation effect. Surprisingly, calcium salts produce acamprosate-like effects in all three animal models. We conclude that calcium is the active moiety of acamprosate. Indeed, when translating these findings to the human situation, we found that patients with high plasma calcium levels due to acamprosate treatment showed better primary efficacy parameters such as time to relapse and cumulative abstinence. We conclude that N-acetylhomotaurinate is a biologically inactive molecule and that the effects of acamprosate described in more than 450 published original investigations and clinical trials and 1.5 million treated patients can possibly be attributed to calcium.
authors.affiliation: Institute of Psychopharmacology, Central Institute of Mental Health, University of Heidelberg, Medical Faculty Mannheim, Mannheim, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Spanagel
authors.affiliation: Institute of Psychopharmacology, Central Institute of Mental Health, University of Heidelberg, Medical Faculty Mannheim, Mannheim, Germany.
authors.forename: Valentina
authors.initials: V
authors.lastname: Vengeliene
authors.affiliation: XenoPort, Inc., Santa Clara, CA, USA.
authors.forename: Bernd
authors.initials: B
authors.lastname: Jandeleit
authors.affiliation: XenoPort, Inc., Santa Clara, CA, USA.
authors.forename: Wolf-Nicolas
authors.initials: WN
authors.lastname: Fischer
authors.affiliation: XenoPort, Inc., Santa Clara, CA, USA.
authors.forename: Kent
authors.initials: K
authors.lastname: Grindstaff
authors.affiliation: XenoPort, Inc., Santa Clara, CA, USA.
authors.forename: Xuexiang
authors.initials: X
authors.lastname: Zhang
authors.affiliation: XenoPort, Inc., Santa Clara, CA, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Gallop
authors.affiliation: Florey Institute of Neuroscience & Mental Health, University of Melbourne, Melbourne, Australia.
authors.forename: Elena V
authors.initials: EV
authors.lastname: Krstew
authors.affiliation: Florey Institute of Neuroscience & Mental Health, University of Melbourne, Melbourne, Australia.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Lawrence
authors.affiliation: Department of Addictive Behavior and Addiction Medicine, Central Institute for Mental Health, Mannheim, Germany.
authors.forename: Falk
authors.initials: F
authors.lastname: Kiefer
mesh_terms: D000077443:Acamprosate; D000427:Alcohol Deterrents / Q000494:pharmacology / Q000627:therapeutic use*; D000437:Alcoholism / Q000188:drug therapy* / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D018683:Excitatory Amino Acid Agents / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D018682:GABA Agents / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000235:genetics; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics / Q000378:metabolism; D055502:Secondary Prevention; D013654:Taurine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use; D014982:Xenopus laevis
chemical_list: D000427:Alcohol Deterrents; D018683:Excitatory Amino Acid Agents; D018682:GABA Agents; D016194:Receptors, N-Methyl-D-Aspartate; D013654:Taurine; D000077443:Acamprosate; D002118:Calcium